20,345 reputation
12787
bio website
location Paris, France
age
visits member for 3 years, 2 months
seen 38 mins ago

I'm an engineer with experience in applied cryptography, in particular in Smart Card systems.


Oct
6
revised Is there a string that's hash is equal to itself?
Also answer an alternate reading of the question
Oct
6
comment Is there a string that's hash is equal to itself?
I think that the argument about left bit rotation making a solution impossible for MD5 is plain wrong.
Oct
6
answered Is there a string that's hash is equal to itself?
Oct
6
revised Is this chat protocol safe?
Somewhat reformat (not be construed as an endorsment)
Oct
4
revised Does omitting the first two lines of RC4's pseudo-random generation algorithm weaken the cipher?
Polish
Oct
3
revised Has there been any cryptanalysis of AES under a non-uniformly distributed key?
Restructure
Oct
3
revised Has there been any cryptanalysis of AES under a non-uniformly distributed key?
Polish
Oct
3
revised Has there been any cryptanalysis of AES under a non-uniformly distributed key?
Expected difficulty of attack should be adjusted according to the entropy remaining after distribution
Oct
3
revised Has there been any cryptanalysis of AES under a non-uniformly distributed key?
Add link to Dmitry Hhovratovich's user page
Oct
3
comment Has there been any cryptanalysis of AES under a non-uniformly distributed key?
@Seth: If my understanding is correct, even in the hypothesis you describe, we do not know an attack better than brute force; and that holds even if we allow the attacker to define how the key is expanded (without loss of entropy). I'm not sure of that, but still turned it into a tentative answer.
Oct
3
answered Has there been any cryptanalysis of AES under a non-uniformly distributed key?
Oct
2
answered What is the translation for “hash” in french?
Oct
2
comment How did the power measurements translate to AES Key?
It may help to read Paul Kocher, Joshua Jaffe, Benjamin Jun, Pankaj Rohatgi's Introduction to differential power analysis, in Journal of Cryptographic Engineering (2011).
Oct
2
revised Small Encryption Exponent
Revise hint 2, minor polish
Oct
2
comment Strength of MD5 in finding duplicate files
In addition: for file de-duplication, we can use MD5 with a secret initial state (or equivalently a 32-byte prefix to the hashed file) drawn randomly at initialization of the de-duplication utility. Now, despite MD5 known weaknesses, one not knowing the secret can't prepare two different files with the same hash. $\;$ Note: if the adversary could examine the hashes, it is better to use full-blown HMAC-MD5, which is nearly as efficient.
Oct
2
revised Small Encryption Exponent
Add another hint. Tone down the avaiability of means to factor a 384-bit number in 1995
Oct
2
comment How does Blowfish avoid successful cryptanalysis?
@owlstead: Can you give reference? I am not aware of attacks on the Blowfish algorithm (rather than: implementations thereof) which would represent a sizable threat in any semi-realistic use case. For example, I can't imagine an attacker exploiting Orhun Kara and Cevat Manap's A New Class of Weak Keys for Blowfish (in proceedings of FSE 2007). I'm rather on the impression that Blowfish is a rather fine cipher except for having a 64-bit block, lack of key agility, relatively high RAM usage, and significant hardware footprint.
Oct
1
revised Small Encryption Exponent
Adress the doomed attempt discussed in the question
Oct
1
revised Small Encryption Exponent
Polish again
Oct
1
revised Small Encryption Exponent
Polish